1. Field of the Invention
The present invention relates to a composition for the prevention and treatment of autoimmune diseases comprising a double antagonist to TNF-α and IL-21.
2. Description of the Related Art
Immune system plays a role in protecting human body from antigens, the harmful foreign materials. Such antigens are exemplified by bacteria, viruses, toxic materials, cancer cells, and blood or tissues of other people or animals. Immune system produces antibodies to destroy such harmful foreign materials introduced. However, if immune system is mal-functioning, the system cannot distinguish normal health organs of its own from harmful foreign antigens, and thus it destroys normal tissues as well. This reaction is called autoimmune disease. Such reaction shows allergic hypersensitivity reaction. Allergy is the reaction against foreign materials that are not harmful for human body, but in the case of autoimmune disease, reaction target includes normal tissues. The reason why immune system cannot distinguish normal organs from antigens is not known. There is only assumed theory that microorganisms such as bacteria or drugs might cause such disease in those who are inherited specifically with such genes that are vulnerable to autoimmune disease.
Autoimmune disease is exemplified by Hashimoto's thyroiditis, pernicious anemia, Addison's disease, type 1 diabetes, Rheumatoid arthritis, Systemic lupus erythematosus, dermatomyositis, Sjogren syndrome, Lupus erythematosus, Multiple sclerosis, Myasthenia gravis, Reactive arthritis, Grave's disease, and Celiac disease—sprue, etc.
The purpose of the treatment of autoimmune disease is to regulate autoimmune response and to recover damaged immune function. The treatment method can be varied from the type of autoimmune disease. For example, if there is a problem in blood, blood transfusion is required. If any abnormality is observed in bone, joint, or muscle, physical exercise or other functional treatment is required. In addition, drug is prescribed in order to regulate immune response. Such drug is called immunosuppressive medicine, which is exemplified by corticosteroids such as prednisone and nonsteroids such as cyclophosphamide, azathioprine, and tacrolimus, etc.
Even though 21 million people world-widely, which are approximately 1% of the total population on earth, catch rheumatoid arthritis (RA), one of autoimmune disease, the reason of this disease has not been disclosed, yet. The symptom of rheumatoid arthritis is symmetric systemic chronic inflammation in diarthrodial joint. When it gets worse, even joint dysfunction occurs. Make matter worse, such mal-functioning of autoimmune system brings inflammation and pain not only in joint but also in other tissues around joint and further in other organs of entire body including lung, skin, and eye with causing pain and osteoporosis, resulting in severe decrease of life-quality making normal daily life impossible.
The previous treatment of rheumatoid arthritis focused on delaying the development of the disease or alleviating the accompanied pain by the improvement of life habit, surgical operation, and administration of a therapeutic agent, with inhibiting infection but without expecting any improvement of joint functions. However, the recent treatment is aiming at the full recovery of joint function. This has been made possible by the development of anti-TNF antagonists, which has been regarded most dramatic discovery for the treatment of rheumatoid arthritis.
Tumor necrosis factor (TNF) is the pleiotropic cytokine, which plays an important role not only in inflammatory reaction but also in immune system. It is found in the joint of rheumatoid arthritis patient and colon of Crohn's disease patient. It has also been reported that tumor necrosis factor plays an important role in osteoclast, too. Therefore, all the treatment agents have been developed in order to inhibit TNF activity, precisely to interrupt signal transduction by binding to ligand belonging to TNF superfamily or to interrupt the bond between TNF ligand and receptor. To inhibit TNF signal transduction, monoclonal antibody against TNF ligand or recombinant protein has been used. Precisely, the treatment method using monoclonal antibody such as infliximab (Remicade) or adalimumab (Humira) has been used. And the treatment method using recombinant protein such as CTLA-4 Ig or entracept (Enbrel) has been also used. Infliximab, entracept, and adalimumab are the biological agents first accredited as rheumatoid arthritis treatment agents, which have been used for the past 10 years showing high efficiency. In addition to TNF, other cytokines have been targeted to develop a treatment agent. As DMARD (disease-modifying anti-rheumatic drugs) inhibiting interleukin, treatment agents have been developed targeting IL-6 or IL-1. However, the treatment effect is not as good as those of the anti-TNF agents.
Despite the excellent treatment effect, the anti-TNF agents have many problems to overcome. One example is the side effect of the administration of anti-TNF agents, which is TNF mechanism is stopped working, leading to mal-functioning of immune system with increasing risk of fungal or viral infection. Particularly, the chance of recurrence of dormant tuberculosis increases. In addition, demyelinating disorder such as multiple sclerosis or hematologic malignancies might be caused. According to rheumatoid society, chances of skin cancer development are higher in rheumatoid arthritis patients administered with anti-TNF agents than in those treated with the conventional therapeutic agents.
The treatment effect of the agent is not all the same among rheumatoid arthritis patients. Two thirds of the patients showed treatment effect, but one third of the patients were not improved. This result indicates that the treatment is limited by the medical history or genetic factors. Not only the pain from the disease but also the side effects accompanied by the treatment and the safety problems have to be considered and overcome. In the case of pregnant women having rheumatoid arthritis, the safety of fetus has been an issue when anti-TNF agent is administered. Scientists are faced with the task of developing diagnostic method to predict the treatment effect and the side effects thereby.
Interleukin (IL) is a kind of cytokine, which acts as a chemical signal between red blood cells. IL-2 was approved by FDA in 1992 for the treatment of liver cancer in late stage. At that time, it was the first single immunotherapeutic agent. Since then, IL-2 has been used in the treatment of metastatic melanoma, too. IL-2 itself was used for the treatment of cancer or co-treated with vaccine. IL-2 helps immune system working to grow or differentiate cells fast. However, side effects have also been reported such as chills, fever, and fatigue, similar to those accompanied by cold, and confusion. IL-15 and IL-21, belonging to IL-2 family, have been studied as single cancer treatment agents or as adjuvants.
IL-21 is a kind of cytokine having α-helix structure. This cytokine induces inflammatory reaction in the middle of signal transduction using IL-21 receptor and γ-chain. IL-21 has been known to induce the maturation of NK cell precursors in bone marrow (Parrish-Novak J., et al., Nature, 408: 57-63, 2000). Particularly, IL-21 is reported to increase effector functions such as cytokine productivity and apoptotic activity of NK cells (Strengell M, et al., J Immunol., 170: 5464-5469, 2003; Brady J, et al., J Immunol., 172: 2048-2058, 2004). It also increases the effect of CD8+ T cells to accelerate anti-cancer response in endogenous adaptive immune system (Takaki R., et al., J Immunol., 175: 2167-2173, 2005; Moroz A., et al., Immunol, 173: 900-909, 2004). IL-21 is also reported to activate NK cells separated from human peripheral blood (Parrish-Novak J., et al., Nature, 408: 57-63, 2000) and play an important role in inducing mature NK cells from hematopoietic stem cells separated from cord blood (Sonia A. P, et al., Int. immunol., 18: 49-58, 2006).
The present inventors tried to develop a novel therapeutic agent for autoimmune disease which is advantageous in overcoming the limitation of efficiency and safety matter of the conventional single antagonist used as an anti-TNF treatment agent. Precisely, the inventors constructed TNFR2-IL21R fusion protein having antagonism against TNF-alpha (α) and IL-21. Then, the inventors confirmed with the fusion protein that the expressions of inflammatory cytokines such as IL-21 and IL-17 and RORc were all reduced but the expression of FoxP3 and the secretion of anti-inflammatory cytokine IL-10 were increased. The inventors further confirmed that TNFR2-IL21R fusion protein inhibited the differentiation of osteoclasts and reduced the expression of cathespin K, which was greater than when TNFR2-Fc or IL21R-Fc was treated. In CIA (collagen induced arthritis) mouse model, the present inventors confirmed that the TNFR2-IL21R fusion protein of the invention had not only arthritis treatment effect but also autoimmune arthritis treatment effect by increasing the expression of immune inhibitor Treg cells. The present inventors finally completed this invention by confirming the great possibility of the TNFR2-IL21R fusion protein of the invention as a treatment agent for autoimmune rheumatoid arthritis.